Vulnerability-Lookup

GHSA-5RFV-H47G-XJ42

Vulnerability from github – Published: 2026-04-09 12:31 – Updated: 2026-04-29 20:38

Summary

Mattermost MS Teams plugin doesn't limit the request body size on the /changes webhook endpoint

Details

Mattermost Plugins versions <=2.1.3.0 fail to limit the request body size on the {{/changes}} webhook endpoint which allows an authenticated attacker to cause memory exhaustion and denial of service via sending an oversized JSON payload. Mattermost Advisory ID: MMSA-2026-00611.

Severity

6.5 (Medium)


                  
                    CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Show details on source website

JSON

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{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/mattermost/mattermost-plugin-msteams"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.15.1-0.20260213190728-6fe4d295592e"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-24661"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-770"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-29T20:38:59Z",
    "nvd_published_at": "2026-04-09T11:16:21Z",
    "severity": "MODERATE"
  },
  "details": "Mattermost Plugins versions \u003c=2.1.3.0 fail to limit the request body size on the {{/changes}} webhook endpoint which allows an authenticated attacker to cause memory exhaustion and denial of service via sending an oversized JSON payload. Mattermost Advisory ID: MMSA-2026-00611.",
  "id": "GHSA-5rfv-h47g-xj42",
  "modified": "2026-04-29T20:38:59Z",
  "published": "2026-04-09T12:31:11Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-24661"
    },
    {
      "type": "WEB",
      "url": "https://github.com/mattermost/mattermost-plugin-msteams/commit/6fe4d295592ecc8767d67e69286cbeec01be3210"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/mattermost/mattermost-plugin-msteams"
    },
    {
      "type": "WEB",
      "url": "https://github.com/mattermost/mattermost-plugin-msteams/releases/tag/v2.3.2"
    },
    {
      "type": "WEB",
      "url": "https://mattermost.com/security-updates"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Mattermost MS Teams plugin doesn\u0027t limit the request body size on the /changes webhook endpoint"
}

CVE-2026-24661 (GCVE-0-2026-24661)

Vulnerability from cvelistv5 – Published: 2026-04-09 10:12 – Updated: 2026-04-09 11:44

Title

Unbounded Request Body Read in MS Teams Plugin {{/changes}} Webhook Endpoint

Summary

Severity

3.7 (Low)


                        
                          CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-04-09 11:44 UTC

CWE

CWE-770 - Allocation of Resources Without Limits or Throttling

Assigner

Mattermost CNA under the mitre root

CNA scorecard B 80/100 over 130 records in the last 180 days details

References

1 reference

URL	Tags
https://mattermost.com/security-updates	vendor-advisory

Impacted products

1 product

Vendor	Product	Version
Mattermost	Mattermost	Affected: 0 , ≤ 2.1.3 (semver) Unaffected: 2.3.2.0

Credits

Lorenzo Gallegos

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-24661",
                "options": [
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                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-04-09T11:44:26.767059Z",
                "version": "2.0.3"
              },
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        "providerMetadata": {
          "dateUpdated": "2026-04-09T11:44:35.023Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
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          "defaultStatus": "unaffected",
          "product": "Mattermost",
          "vendor": "Mattermost",
          "versions": [
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              "lessThanOrEqual": "2.1.3",
              "status": "affected",
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          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "Lorenzo Gallegos"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Mattermost Plugins versions \u003c=2.1.3.0 fail to limit the request body size on the {{/changes}} webhook endpoint which allows an authenticated attacker to cause memory exhaustion and denial of service via sending an oversized JSON payload. Mattermost Advisory ID: MMSA-2026-00611"
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "HIGH",
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            "availabilityImpact": "LOW",
            "baseScore": 3.7,
            "baseSeverity": "LOW",
            "confidentialityImpact": "NONE",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L",
            "version": "3.1"
          },
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        "dateUpdated": "2026-04-09T10:12:45.340Z",
        "orgId": "9302f53e-dde5-4bf3-b2f2-a83f91ac0eee",
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          "name": "MMSA-2026-00611",
          "tags": [
            "vendor-advisory"
          ],
          "url": "https://mattermost.com/security-updates"
        }
      ],
      "solutions": [
        {
          "lang": "en",
          "value": "Update Mattermost Plugins to versions 2.3.2.0 or higher."
        }
      ],
      "source": {
        "advisory": "MMSA-2026-00611",
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          "https://mattermost.atlassian.net/browse/MM-67561"
        ],
        "discovery": "{\"self\"=\u003e\"https://mattermost.atlassian.net/rest/api/2/customFieldOption/10557\", \"value\"=\u003e\"Internal\", \"id\"=\u003e\"10557\"}"
      },
      "title": "Unbounded Request Body Read in MS Teams Plugin {{/changes}} Webhook Endpoint",
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        "engine": "cvelib 1.8.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "9302f53e-dde5-4bf3-b2f2-a83f91ac0eee",
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    "datePublished": "2026-04-09T10:12:45.340Z",
    "dateReserved": "2026-02-11T20:56:06.566Z",
    "dateUpdated": "2026-04-09T11:44:35.023Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Vulnerability timeline

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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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